Although the complicated mechanisms of DDD pathogenesis remain elusive, several key molecules and signaling pathways have been linked to the initiation and progression of DDD, which include but are not limited to Wnt/β-catenin, TGF-β/Smads, TNFα/NFκB, NLRP3/IL-1β, hypoxia-induced factors (HIFs), fibroblast growth factor (FGF), and FA signaling pathways [10, 42, 45-52]. Here, TGFB1 is linked to Dowling-Degos disease 1.